The present invention relates to a powder supply system for supplying powder, and more specifically, to the powder supply system for replenishing powder in a plurality of powder supply units.
Conventionally, a plurality of powder supply units for supplying powder at various stages along a production line have been provided at different locations along the production line. For example, in a production line such as a line for producing bread, a plurality of powder supply units are provided each in association with each processing device, so that powders in the powder supply unit are sprinkled on the surface of dough at the processing device.
According to a conventional powder supply system, a powder replenishment device or a powder replenishment device having a pressure source has been provided for supplying powder to each one of the plurality of powder supply units to replenish powder in the powder supply units. The plurality of the powder supply units are connected to the powder replenishment device by pipes arranged in parallel. Pressurized air from the pressure source is used to supply powder to the plurality of powder supply units.
The pressure source generates a high pressure to create and air flow in the pipes sufficient for moving the powder through the pipes. Therefore, the piping must be highly resistant to high pressure. Also, the portions where separate pipes are connected together need to be maintained with a proper seal. The configuration for maintaining the seal becomes complicated to withstand the high pressure in the pipes.
Japanese Laid-Open Patent Application (Kokai) No. SHO-63-272720 discloses a configuration for transporting powder using a flow of air caused by suction force generated by a suction unit. Utilization of the negative pressure can avoid problems attendant to the utilization of highly positive pressure.
However, in these conventional configurations for replenishing powder from the powder replenishment device to each of the plurality of powder supply units, the plurality of powder supply units are connected in parallel with respect to the powder replenishment device whether the configuration is for supplying powder by pressurized air or by suction of air. This parallel construction requires branch pipes for distributing powder from the powder replenishment device to the individual powder supply units. This complicates the piping arrangement for transporting powder. Further, a switching valve for switching transport of powder to each of the powder supply units must be provided to each powder supply unit or to each branch pipe portion. This can make the overall cost of piping expensive.